Python语言及其应用（第2版）

文件和目录

｜

237

img.save(fp, fmt) # 写入内存

return fp.getvalue()

def convert_image(data, fmt=None):

"""Convert image <data> to PIL <fmt> image data"""

img = data_to_img(data)

return img_to_data(img, fmt)

def get_file_data(name):

"""Return PIL Image object for image file <name>"""

img = Image.open(name)

print("img", img, img.format)

return img_to_data(img)

if __name__ == "__main__":

for name in sys.argv[1:]:

data = get_file_data(name)

print("in", len(data), data[:10])

for fmt in ("gif", "png", "jpeg"):

out_data = convert_image(data, fmt)

print("out", len(out_data), out_data[:10])

因为是类文件对象，所以可以像对待普通文件那样对

BytesIO

对象调用

seek()

、

read()

和

write() ...